[PATCH v6 2/3] leds: flash: rt8515: Support single-GPIO flash ICs with vin supply
From: Rudraksha Gupta via B4 Relay
Date: Wed May 27 2026 - 22:35:41 EST
From: Rudraksha Gupta <guptarud@xxxxxxxxx>
Extend the RT8515 driver to support flash ICs that use only a single
GPIO for both flash and torch modes (no separate ENT pin), with an
optional vin regulator that gates power to the flash IC.
When vin-supply is provided, the driver enables the regulator before
activating the LED and disables it when turning off.
Make ent-gpios optional. When ent-gpios is absent, the driver uses
enf-gpios for both flash and torch brightness control.
Assisted-by: Claude:claude-opus-4.6
Reviewed-by: Linus Walleij <linusw@xxxxxxxxxx>
Signed-off-by: Rudraksha Gupta <guptarud@xxxxxxxxx>
---
drivers/leds/flash/leds-rt8515.c | 148 +++++++++++++++++++++++++++++----------
1 file changed, 112 insertions(+), 36 deletions(-)
diff --git a/drivers/leds/flash/leds-rt8515.c b/drivers/leds/flash/leds-rt8515.c
index f6b439674c03..0fb84d98211d 100644
--- a/drivers/leds/flash/leds-rt8515.c
+++ b/drivers/leds/flash/leds-rt8515.c
@@ -31,6 +31,7 @@
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
+#include <linux/workqueue.h>
#include <media/v4l2-flash-led-class.h>
@@ -44,6 +45,9 @@
#define RT8515_TIMEOUT_US 250000U
#define RT8515_MAX_TIMEOUT_US 300000U
+#define RT8515_OFF 0
+#define RT8515_ON 1
+
struct rt8515 {
struct led_classdev_flash fled;
struct device *dev;
@@ -52,7 +56,7 @@ struct rt8515 {
struct regulator *reg;
struct gpio_desc *enable_torch;
struct gpio_desc *enable_flash;
- struct timer_list powerdown_timer;
+ struct delayed_work powerdown_work;
u32 max_timeout; /* Flash max timeout */
int flash_max_intensity;
int torch_max_intensity;
@@ -63,27 +67,57 @@ static struct rt8515 *to_rt8515(struct led_classdev_flash *fled)
return container_of(fled, struct rt8515, fled);
}
-static void rt8515_gpio_led_off(struct rt8515 *rt)
+static int rt8515_gpio_led_off(struct rt8515 *rt)
{
- gpiod_set_value(rt->enable_flash, 0);
- gpiod_set_value(rt->enable_torch, 0);
+ int ret = 0;
+
+ gpiod_set_value(rt->enable_flash, RT8515_OFF);
+ gpiod_set_value(rt->enable_torch, RT8515_OFF);
+
+ if (!rt->reg)
+ return ret;
+
+ ret = regulator_is_enabled(rt->reg);
+ if (ret > 0)
+ ret = regulator_disable(rt->reg);
+
+ return ret;
}
-static void rt8515_gpio_brightness_commit(struct gpio_desc *gpiod,
- int brightness)
+static int rt8515_gpio_brightness_commit(struct rt8515 *rt, struct gpio_desc *gpiod, int brightness)
{
int i;
+ int ret;
+
+ /*
+ * Reset the IC to start brightness from zero,
+ * then re-enable and pulse to the desired level.
+ */
+ ret = rt8515_gpio_led_off(rt);
+ if (ret)
+ return ret;
+
+ /* IC needs time to reset its brightness counter */
+ usleep_range(100, 200);
+
+ if (rt->reg) {
+ ret = regulator_enable(rt->reg);
+ if (ret)
+ return ret;
+ }
/*
* Toggling a GPIO line with a small delay increases the
* brightness one step at a time.
*/
for (i = 0; i < brightness; i++) {
- gpiod_set_value(gpiod, 0);
+ gpiod_set_value(gpiod, RT8515_OFF);
udelay(1);
- gpiod_set_value(gpiod, 1);
+ gpiod_set_value(gpiod, RT8515_ON);
udelay(1);
}
+
+ return 0;
}
/* This is setting the torch light level */
@@ -92,23 +126,38 @@ static int rt8515_led_brightness_set(struct led_classdev *led,
{
struct led_classdev_flash *fled = lcdev_to_flcdev(led);
struct rt8515 *rt = to_rt8515(fled);
+ int ret = 0;
mutex_lock(&rt->lock);
if (brightness == LED_OFF) {
/* Off */
- rt8515_gpio_led_off(rt);
+ ret = rt8515_gpio_led_off(rt);
+ if (ret)
+ goto out;
} else if (brightness < RT8515_TORCH_MAX) {
- /* Step it up to movie mode brightness using the flash pin */
- rt8515_gpio_brightness_commit(rt->enable_torch, brightness);
+ /*
+ * Step it up to movie mode brightness.
+ * If there is no separate torch pin, use the flash pin
+ * for torch as well.
+ */
+ ret = rt8515_gpio_brightness_commit(rt,
+ rt->enable_torch ?: rt->enable_flash, brightness);
+ if (ret)
+ goto out;
} else {
- /* Max torch brightness requested */
- gpiod_set_value(rt->enable_torch, 1);
+ /*
+ * Max torch brightness requested.
+ * If there is no separate torch pin, use the flash pin
+ * for torch as well.
+ */
+ gpiod_set_value(rt->enable_torch ?: rt->enable_flash, RT8515_ON);
}
+out:
mutex_unlock(&rt->lock);
- return 0;
+ return ret;
}
static int rt8515_led_flash_strobe_set(struct led_classdev_flash *fled,
@@ -117,27 +166,36 @@ static int rt8515_led_flash_strobe_set(struct led_classdev_flash *fled,
struct rt8515 *rt = to_rt8515(fled);
struct led_flash_setting *timeout = &fled->timeout;
int brightness = rt->flash_max_intensity;
+ int ret = 0;
- mutex_lock(&rt->lock);
-
- if (state) {
- /* Enable LED flash mode and set brightness */
- rt8515_gpio_brightness_commit(rt->enable_flash, brightness);
- /* Set timeout */
- mod_timer(&rt->powerdown_timer,
- jiffies + usecs_to_jiffies(timeout->val));
- } else {
- timer_delete_sync(&rt->powerdown_timer);
+ if (!state) {
+ cancel_delayed_work_sync(&rt->powerdown_work);
+ mutex_lock(&rt->lock);
/* Turn the LED off */
- rt8515_gpio_led_off(rt);
+ ret = rt8515_gpio_led_off(rt);
+ if (!ret)
+ fled->led_cdev.brightness = LED_OFF;
+ mutex_unlock(&rt->lock);
+ return ret;
}
+ mutex_lock(&rt->lock);
+
+ /* Enable LED flash mode and set brightness */
+ ret = rt8515_gpio_brightness_commit(rt, rt->enable_flash, brightness);
+ if (ret)
+ goto out;
+
+ /* Set timeout */
+ schedule_delayed_work(&rt->powerdown_work, usecs_to_jiffies(timeout->val));
+
fled->led_cdev.brightness = LED_OFF;
/* After this the torch LED will be disabled */
+out:
mutex_unlock(&rt->lock);
- return 0;
+ return ret;
}
static int rt8515_led_flash_strobe_get(struct led_classdev_flash *fled,
@@ -145,7 +203,7 @@ static int rt8515_led_flash_strobe_get(struct led_classdev_flash *fled,
{
struct rt8515 *rt = to_rt8515(fled);
- *state = timer_pending(&rt->powerdown_timer);
+ *state = delayed_work_pending(&rt->powerdown_work);
return 0;
}
@@ -163,12 +221,18 @@ static const struct led_flash_ops rt8515_flash_ops = {
.timeout_set = rt8515_led_flash_timeout_set,
};
-static void rt8515_powerdown_timer(struct timer_list *t)
+static void rt8515_powerdown_work(struct work_struct *work)
{
- struct rt8515 *rt = timer_container_of(rt, t, powerdown_timer);
+ struct rt8515 *rt = container_of(work, struct rt8515, powerdown_work.work);
+ int ret;
/* Turn the LED off */
- rt8515_gpio_led_off(rt);
+ mutex_lock(&rt->lock);
+ ret = rt8515_gpio_led_off(rt);
+ mutex_unlock(&rt->lock);
+
+ if (ret)
+ dev_err(rt->dev, "failed to turn off LED (%d)\n", ret);
}
static void rt8515_init_flash_timeout(struct rt8515 *rt)
@@ -298,11 +362,18 @@ static int rt8515_probe(struct platform_device *pdev)
return dev_err_probe(dev, PTR_ERR(rt->enable_flash),
"cannot get ENF (enable flash) GPIO\n");
- /* ENT - Enable Torch line */
- rt->enable_torch = devm_gpiod_get(dev, "ent", GPIOD_OUT_LOW);
+ /* ENT - Enable Torch line (optional for single-GPIO flash ICs) */
+ rt->enable_torch = devm_gpiod_get_optional(dev, "ent", GPIOD_OUT_LOW);
if (IS_ERR(rt->enable_torch))
return dev_err_probe(dev, PTR_ERR(rt->enable_torch),
- "cannot get ENT (enable torch) GPIO\n");
+ "Failed to obtain the Enable Torch GPIO\n");
+
+ rt->reg = devm_regulator_get_optional(dev, "vin");
+ if (IS_ERR(rt->reg)) {
+ if (PTR_ERR(rt->reg) == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
+ rt->reg = NULL;
+ }
child = device_get_next_child_node(dev, NULL);
if (!child) {
@@ -328,12 +399,17 @@ static int rt8515_probe(struct platform_device *pdev)
dev_warn(dev,
"flash-max-timeout-us property missing\n");
}
- timer_setup(&rt->powerdown_timer, rt8515_powerdown_timer, 0);
+ INIT_DELAYED_WORK(&rt->powerdown_work, rt8515_powerdown_work);
rt8515_init_flash_timeout(rt);
fled->ops = &rt8515_flash_ops;
- led->max_brightness = rt->torch_max_intensity;
+ /*
+ * If there is no separate torch pin, use flash max intensity
+ * as max brightness instead.
+ */
+ led->max_brightness = rt->enable_torch ?
+ rt->torch_max_intensity : rt->flash_max_intensity;
led->brightness_set_blocking = rt8515_led_brightness_set;
led->flags |= LED_CORE_SUSPENDRESUME | LED_DEV_CAP_FLASH;
@@ -372,7 +448,7 @@ static void rt8515_remove(struct platform_device *pdev)
struct rt8515 *rt = platform_get_drvdata(pdev);
rt8515_v4l2_flash_release(rt);
- timer_delete_sync(&rt->powerdown_timer);
+ cancel_delayed_work_sync(&rt->powerdown_work);
mutex_destroy(&rt->lock);
}
--
2.54.0